A mullite-based sintered body shows minor deterioration in strength at high temperatures, and has been under focus as a ceramic for high temperature structural use and is used as a refractory for sintering furnaces or the like.
In comparison to alumina or the like, a mullite-based sintered body has a small thermal expansion coefficient and the thermal expansion coefficient is similar to those of semiconductor devices such as Si, gallium arsenide, and the like, it has been targeted as an insulating substrate material for integrated circuits (for example, see Patent Document 1). In recent years, it has been subjected to attempts to apply the sintered-based body to an inspection apparatus (called a probe card) that is capable of simultaneously testing the electrical characteristics of a plurality of semiconductor elements all together while in a semiconductor wafer state (for example, patent document 2).